Electrodes for gas plasma display panels and method of manufacture thereof

ABSTRACT

An electrode stack for gas plasma display panels comprises a plurality of dielectric plates each having tapered apertures therethrough. A metal film deposited on the surface of each plate that contains the narrow ends of the tapered apertures provides display electrodes, the film being deposited up to the peripheral edges of the apertures. The plates are stacked with respect to each other such that the surfaces of the plates containing the narrow ends of the apertures are adjacent to surfaces of other plates containing the wide ends of the apertures thereby exposing an effective metal electrode surface. A method involving a single-sided etching technique for manufacturing the electrode structure is disclosed.

Armstrong Dec. 4, 1973 ELECTRODES FOR GAS PLASMA DISPLAY PANELS AND METHOD OF Primary Examiner-Roy Lake NUF RE R O Assistant Examinerl-lugh D. Jaeger [75] Inventor: James B. Armstrong, Phoenix, Ariz. Aimmey Howard Terry [73] Assignee: Sypergylznd Corporation, New [57] ABSTRACT or An electrode stack for gas plasma displaypanels com- [22] led: 1972 prises a plurality of dielectric plates each having ta- 21 App] 237 722 pered apertures therethrough. A metal film deposited on the surface of each plate that contains the narrow ends of the tapered apertures provides display elec- [52] [1.8. CI. 3.13/2l7, 315/169 R trodes the l being deposited p to the peripheral [51] Int. Cl H01 17/04, H01 J 61/30 edges of the apertures The plates are stacked with [58] Field Of Search 313/217, 220, 218; I Spect to each other Such that the Surfaces of the plates 315/169 R containing the narrow ends of the apertures are adjacent to surfaces of other plates containing the wide [56] References and ends of the apertures thereby exposing an effective UNITED STATES PATENTS metal electrode surface. A method involving a single- 3,700,946 10 1972 Caras 313 217 x Sided etching technique for manufacturing the elec- 3,560,790 2/1971 Vollmer. 313/217 X trode structure is disclosed. 3,701,924 10/1972 G1aser.... 315/169 R X 3,619,698 11 1971 Caras 315/169 R x 4 C 6 Drawing Figures A [20 I 1S5 V J V J l Y 31(2) \V V \& 1 1 I V V (/A V fl V /f\ V /I V Y A \V L21 \y V fl V/// V\ l /l j/V A W Z 15 x PATENTED DEC 75 sum 2 0F 3v ELECTRODES FOR GAS PLASMA DISPLAY PANELS AND METHOD OF MANUFACTURE THEREOF BACKGROUND OF THE INVENTION 1. Field of the Invention The invention pertains to electrode structures particularly with regard to stacked electrode structures for use in gas plasma panel displays'and other devices embodying similar stacked electrode structures.

2. Description of the Prior Art U.S. Pat. application Ser. No. 90,538 filed Nov. 18, 1970, Digitally Addressable Gas Discharge Display Apparatus, by Claude D. Lustig and Albert W. Baird III and assigned to the assignee of the present invention, discloses a gas plasma display panel having a stack of addressing anodes comprising a plurality of thin metal anode plates having a matrix of apertures therethrough. Interposed between each electrode plate is a thin dielectric insulating plate, typically of glass material, having a matrix of holes corresponding to and aligned with those of the metal plates. Gas discharge columns are selectively extended through the apertures from a gas plasma reservoir to a plurality of display cells by selective application of addressing potential to the portions of the addressing anodes. The selectively extended gas plasma columns ignite discharges in the display cells thereby providing selected information patterns.

Although the stack of addressing anodes is reasonably economical to manufacture and has acceptable thickness when assembled, manufacturing economies and diminution in the thickness of the electrode stack may be effected by replacing the interleaved metal electrode plates and glass insulators with a stack of apertured dielectric plates with metal electrode films deposited on the surfaces thereof. It was discovered, however, that control of the gas discharge columns was not sufficiently effective since only the thin edges of the metal film exposed at the peripheries of the apertures provided the electrode surfaces for the device.

SUMMARY OF THE INVENTION Significantly greater control effectiveness of the deposited metal film electrodes is achievable by utilizing tapered apertures through the dielectric plates. The metal layer electrodes are deposited on the surfaces of the plates containing the narrow ends of the tapered apertures, the metal layers extending up to the peripheral edges of the apertures. The metalized plates are stacked with respect to each other such that the surfaces of the plates containing the narrow ends of the apertures are adjacent to the surfaces of plates containing the wide ends of the apertures thereby exposing an effective metal electrode surface to the gas plasma columns. A method of manufacturing the electrodes involving a single sided etching technique is utilized.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. la-lb are an exploded perspective view of the 4 gas-plasma display panel of said Ser. No. 90,538 in which the present invention may be utilized.

FIG. 2 is a side elevation view in section of a portion of the addressing electrode stack of FIG. 1 in accordance with the invention.

FIG. 3 is a perspective view of one of the tapered apertures in accordance with the invention.

'FIG. 4 is a side elevation view in section illustrating the single-sided etching technique utilized in manufacturing the tapered aperture.

Fig. 5 is a perspective view ofa conventional cylindrical aperture resulting from the conventional doublesided etching process.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, agasplasma display panel 10 of the type described in said Ser. No. 90,538 is illustrated. Since the structure and operation of the display 10 is explained in-detailin said Ser. No. 90,538, only abrief description will be provided herein for brevity.

The gas plasma display panel 10 is comprised of a reservoir 11 of ionizable gas, a stack of addressing anodes 12 and a plurality of display cells 13. The stack .of addressing anodes 12 is comprised of a plurality of dielectric plates which may, for example, be suitably composed of glass. Each of the plates 14 has a plurality of apertures therethrough forming a matrix of channels extending from the reservoir 11 to the display cells 13 in the manner and for the reasons described in said Ser. No. 90,538. Each of the dielectric plates 14 has a metal film l5 deposited on the surface thereof facing the reservoir 11 which films 15 are deposited in patterns so as to functionas the addressing anodes for the display device 10 in the manner described in said Ser. No.

As previously explained, if cylindrically sided apertures are utilized through the plates 14, only the thin edges of the metal film will be exposed at the apertures thereby providing ineffective control of the gas plasma columns. This ineffectivenes occurs since, in order to extend a gas plasma column from the reservoir 11, current must be drawn through the metal electrodes. Because the metalization is thin and confined to the flat surfaces of the dielectric plate 14, the metalization is exposed to the passage of plasmathrough the stack 12 in edge-on fashion with only a small area of metal exposed to the plasma. This arrangement, coupled with the thinness of the metalization, presents a relatively high resistivity to the passage of the current resulting in ineffective control of the plasma. The metalization must be confined to the flat surfaces of the dielectric plates 14 since it is relatively difficult in manufacture to metalize within the apertures and maintain layer-tolayer electrical isolation. The metal electrode surface exposed to the plasma is increased in accordance with the invention by utilizing tapered plates 14.

Referring now to FIG. 2 in which like reference numerals indicate like components with respect to FIG. 1, a side elevation view, in section, of several of the plates 14 with the metalizing 15 deposited thereon is illustrated. As previously described, each of the plates 14 has a matrix of tapered apertures 20 therethrough, which apertures may, for example, be conically shaped. The metal film 15 is deposited on the flat surface of each plate 14 that contains the narrow ends of the .ta-

7 pered apertures 20. The plates 14are stacked with respect to each other such that the surfaces of the plates 14 containing the narrow ends of the apertures 20 are adjacent the surfaces of the plates 14 containing the wide ends thereof. The apertures 20 through the plates 14 are aligned such that portions 21 of the metal electrodes 15 are exposed where the wide ends of the aperapertures through the tures abut the narrow ends thereof. The plates 14 are preferably oriented so that the gas plasma columns from the reservoir 11 (FIG. 1) impinge upon the apertures 20 in the direction of the arrow A. Thus it is appreciated that significant metal electrode surfaces 21 are exposed to the plasma column thus providing substantially improved control thereof than that provided in the absence of the tapered apertures 20 of the present invention.

It will be appreciated that in addition to the increase in exposed electrode surfaces, the stacked arrangement of tapered apertures of the present invention provides the additional advantage that the layered stack is rendered less sensitive to small deviation in aperture location compared to arrangements absent the invention. This occurs since the area of metal exposed in the aperture does not change even when the apertures in adjacent plates 14 are slightly non-coaxial in alignment. Thus, the electrical properties of the electrode stack are not critically dependent upon the stack alignment.

Referring now to FIG. 3 in which like reference numerals indicate like components with respect to Fig. 2, a perspective view of a portion of a plate 14 showing a conically shaped aperture 20 is illustrated for clarity.

Referring now to FIG. 4, the technique for obtaining the conically shaped apertures 20 is illustrated. The glass plate 14 is coated on one surface with conventional photosensitive etch resistant material 25, the reverse side with a non-sensitized resist material 29. The photo-resist material 25 is removed on one surface of the plate 14 at the location and in the shape of the aperture to be formed as indicated at 26. An alternate method for establishing the etch pattern is to use a metal film deposited on the glass and containing the desired etch pattern produced either by masked deposition of the metal, or by chemical milling of the deposited film after deposition. With a suitable metal and glass etching solution, the patterned metal film may then be used as a resist for the etching of the glass. The plate 14 with the photo-resist coating 25 is then etched in a conventional manner, the dotted lines 27 illustrating the successive stages of the etching process through the aperture 26 in the photo-resist etch resistant layer. This single sided etching process produces an aperture through the plate 14 with sloping sides and in the case where the aperture 26 through the phto-resist material 25 is circular, a conically shaped aperture is produced through the plate 14 as illustrated in FIG. 3.

Subsequent to the etching step, the photo-resist material 25 is removed and the surface 28 of the plate 14 which contains the narrow end of the aperture is metalized to form the control electrodes. These metalized to form the control electrodes. These metalized plates are then stacked as illustrated in FIG. 2 and utilized in a gas plasma display as illustrated in Fig. l.

A further advantage of the invention may be appreciated by consideration of the double-sided chemical etching process conventionally utilized in forming cylindrically shaped apertures in sheet material. In the double-sided technique, the photo-resist material is removed at the location of the aperture from both surfaces of the sheet material whereby the etching process takes place from both surfaces of the sheet toward the center. An aperture, as illustrated in FIG. 5, normally results, this aperture being an approximation to a cylinder. It is appreciated that the effective or minimum diameter of the aperture occurs toward the middle of the sheet whereas in the single-sided etching process, the effective or minimum diameter of the aperture occurs at the narrow end of the aperture at the surface of the plate. Since current must be drawn through the electrode metal and since the thin film electrodes utilized typically exhibit a relatively high lateral resistivity, it is desirable to have a maximum metal area to enhance control efficiency as well as to enhance the uniformity of control parameters within the layers that vary due to voltage drops in the patterned metalized layers. Consequently, when the surface of the plate 14 containing the narrow end of the apertures isused for the metalization, the maximum area of metal and hence the lowest lateral resistance is attained for a given through-hole diameter compared to the more conventional doublesided etched aperture.

Although the invention is described in terms of glass plates with conical apertures etched therethrough, it is appreciated that other dielectric materials may be utilized with conical apertures or other tapered shaped apertures therethrough to the same effect. The hereinabove described embodiment of the invention was explained in terms of the metal film electrodes disposed facing the reservoir of the display panel. It will be appreciated that the reverse arrangement may also be utilized with a diminution in the efi'iciency of the device.

While the invention has been described in its preferred embodiment, it is to be understood that the words which have been used are words of description rather than limitation and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of the invention in its broader aspects.

I claim:

1. An electrode stack for use in a gas plasma display comprising a plurality of dielectric plates each with tapered apertures therethrough, and

metal layer electrode means deposited on the surface of each said plate containing the narrow ends of said tapered apertures, 1

said metal layer electrode means being deposited up to the peripheral edges of said apertures,

said plates being stacked with respect to each other such that the surfaces of said plates containing said narrow ends of said apertures are adjacent the surfaces of said plates containing the wide ends of said apertures,

said apertures being in substantial alignment such that portions of said metal electrode means are exposed where said wide ends of said apertures abut said narrow ends of said apertures.

2. The electrode stack of claim 1 in which said metal layer electrode means comprises a deposited metal film.

3. Gas plasma display apparatus comprising reservoir means for containing an ionizable gas,

a plurality of gas discharge display cell means, and a plurality of electrode means each having a plurality of apertures therethrough,

said plurality of electrode means being in stacked arrangement with respect to each other with said apertures aligned to form a plurality of gas conductive channels extending from said reservoir means to said cell means respectively,

said plurality of electrode means being adapted for connection to sources of selectable electrical potential for selectively applying potentials to said other such that the surfaces of said plates containing said narrow ends of said apertures are adjacent the surfaces of said plates containing the wide ends of said apertures, said apertures being in substantial alignment such that portions of said metal electrode means are exposed where said wide ends of said apertures abut said narrow ends of said apertures.

4. The apparatus of claim 3 wherein said surfaces of said plates containing said narrow ends of said apertures are disposed facing said reservoir means. 

2. The electrode stack of claim 1 in which said metal layer electrode means comprises a deposited metal film.
 3. Gas plasma display apparatus comprising reservoir means for containing an ionizable gas, a plurality of gas discharge display cell means, and a plurality of electrode means each having a plurality of apertures therethrough, said plurality of electrode means being in stacked arrangement with respect to each other with said apertures aligned to form a plurality of gas conductive channels extending from said reservoir means to said cell means respectively, said plurality of electrode means being adapted for connection to sources of selectable electrical potential for selectively applying potentials to said electrode means to selectively extend gas discharge columns in said channels from said reservoir means to said display cell means for igniting gas discharges in selected display cell means, said plurality of electrode means comprising, a plurality of dielectric plates each with tapered apertures therethrough and metal layer electrode means deposited on the surface of each said plate containing the narrow ends of said tapered apertures, said metal layer electrode means being deposited up to the peripheral edges of said apertures, said plates being stacked with respect to each other such that the surfaces of said plates containing said narrow ends of said apertures are adjacent the surfaces of said plates containing the wide ends of said apertures, said apertures being in substantial alignment such that portions of said metal electrode means are exposed where said wide ends of said apertures abut said narrow ends of said apertures.
 4. The apparatus of claim 3 wherein said surfaces of said plates containing said narrow ends of said apertures are disposed facing said reservoir means. 